Variable length and sensor spacing thermistor array

ABSTRACT

An adaptable thermistor array of variable length and sensor spacing. A  pllity of thermistor modules are attached at any desired interval to a braided line. Each thermistor module contains its own power source, sensor, and an acoustic telemetry transmitter to transmit the temperature related data from the module to an acoustic receiver in a buoy from which the line depends.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to obtaining a temperature profile of theupper ocean and more particularly to a variable length and sensorspacing array supported by a remote buoy.

2. Description of the Prior Art

Small remote buoys supporting thermistor arrays have been in use formany years by the oceanographic community to measure the watertemperature profile of the upper ocean. These systems use copperconductors of various lengths to reach thermistors distributed along theaperture of the array. Various techniques are used to incorporate theseinto a cable and, in some cases, a mooring line. However, these arraysare rigidly made for a specific length and sensor spacing, and differentarrays are required for different uses. Further, changes in conductivityof the copper conductors and/or insulation results in temperaturemeasurement uncertainties.

SUMMARY OF THE INVENTION

Accordingly the present invention provides an adaptable thermistor arrayof variable length and sensor spacing. A plurality of thermistor modulesare attached at any desired interval to a braided line. Each thermistormodule contains its own power source, sensor, and an acoustic telemetrytransmitter to transmit the temperature related data from the module toan acoustic receiver in a buoy from which the line depends.

Thus it is an object of the present invention to provide a thermistorarray which can be readily varied as to length and sensor spacing.

Another object of the present invention is to provide a thermistor arraywhich eliminates temperature measurement uncertainties due to changes incopper conductor/insulation conductivity.

Other objects, novel features and advantages will be apparent from thefollowing detailed description when read together with the appendedclaims and attached drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a pictorial view of a temperature profiling system accordingto the present invention.

FIG. 2 is a plan view of a thermistor module attached to a braided lineaccording to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1 a remote buoy 10 is shown on the surface 12 of abody of water. Suspended from the buoy 10 is a line 14 to which areattached a plurality of sensor modules 16 at variable spacings. At theend of the line 14 is a weight 18 to maintain the line in an essentiallyvertical orientation. A mooring cable 20 may be attached to the end ofthe line 16 to form a moored buoy system, and is terminated by an anchor22, such as a heavy chain, on the sea floor 24.

As shown in FIG. 2 the line 14 is braided. The sensor module 16 isretained in a tubular net 26 whose ends are tuck spliced into thebraided line 14. Additionally the ends of the net 26 are seized to theline 14 to assure that the module 16 is securely attached. Each module16 has a sensor 28, such as a thermistor for temperature measurements,an associated electronics package 30 with a clock, a power source 32such as a battery, and an acoustic transmitter 34. These components aresealed or potted in polyurethane in a pipe, such as 3 to 4 inch diameterPVC 8 inches in length, which forms the housing of the module 16. Theremoval of a magnet (not shown) attached to the exterior of the module16 serves to initiate it by releasing an interior contact to energizethe power source 32.

In operation each array can be prepared in the field using standardseamanship techniques. Each module 16 to be attached to a given arrayline 14 has a different frequency for unit identificaton. The modules 16are attached to the line 14 at any desired intervals, the magnets areremoved, and the array is deployed. At periodic intervals, such as every12 hours, determined by the clocks in the respective electronic packageseach xodule 16 transmits its unique frequency modulated in proportion tothe resistance of the thermistor 28. An acoustic receiver in the buoy 10receives the data, processes it for retransmission such as to a standardARGOS satellite. The data may be stored in a recorder and played backupon command. Approximately fifteen modules 16 are required per arraywhich vary in length from 100 meters in the Arctic to 600 meters in theequatorial zones.

Thus, the present invention provides a variable length and sensorspacing thermistor array which can be used in either a free drifting ora xoored configuration to provide periodic temperature profiles in theupper levels of any body of water without degradation due to copperconductor/insulation resistance changes, and which may be readilyconfigured in the field for a specific application using ordinaryseamanship techniques.

What is claimed is:
 1. A variable length and spacing thermistor arraycomprising:a buoy having an acoustic receiver and means forretransmitting data received by said acoustic receiver; a braided linehaving a weight at the end said braided line being suspended from saidbuoy and having a length dependent upon the oceanographic environmentwhere said array is to be deployed; a plurality of thermistor modules,each of said thermistor modules having a thermistor, an acoustictransmitter with a unique frequency, means for sequentially activatingeach of said acoustic transmitters at periodic intervals; means forattaching said thermistor modules to said braided line at variableintervals dependent upon the oceanographic environment where said arrayis to be deployed; and said attaching means comprising a tubular netwithin which said thermistor module is contained, the ends of saidtubular net being woven into and seized onto said braided line.